I've been messing around with the new GW glazes this evening and I must confess that I'm a fan.
One thing that always bugged me was that the Sepia wash over mail created a fairly "dull" golden colour. It looked nice, it's just that sometimes you want to have a brighter, yellower gold.
Using the method described above, it's easy to do now with one extra step. After doing the grayscale thingie and washing with watered (or mediumed) down chainmail or silver, apply some yellow glaze on the areas that you want to be golden. Then apply a coat or two of Sepia (or it's new replacement) and you're good to go, a brighter golden hue that looks rather good
I can also vouch for the red glaze "fixing" the lack of vibrancy of the red wash. As long as you apply the glaze before you apply the wash you will get a more vibrant colour while still retaining the shading/highlight effect of this method. Please note that you still need to mix Baal Red with either a brown or yellowish wash to get rid of the blueish tint. There might also be an application of the orange/yellow shades that just came out but I haven't had time to mess with those yet. I don't have the new Carroburg Red so I can't comment on that yet.